No remedial reply from customer Support


Can anyone tell me how to get a proper answer from Customer support?
I have been communicating with them for over a month over an increase in TOP up limits but not really getting anywhere. I sent supporting documents, wrote a letter and in one case I was informed that they have not received them. Do they not realise that sometimes a human is needed to resolve enquiries. I asked for a phone call and got no reply. Perhaps they have too many new clients without problems!!!